Rss C# WinRT Reference Documentation

Rss

Represents an RSS document or sub-part of a document such as a channel, image, or item. The RSS API allows one to download, create and modify RSS documents.

Object Creation

Chilkat.Rss obj = new Chilkat.Rss();

Properties

public string DebugLogFilePath {get; set; }

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

public string LastErrorHtml {get; }

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

public string LastErrorText {get; }

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

public string LastErrorXml {get; }

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

public bool LastMethodSuccess {get; set; }

Introduced in version 9.5.0.52

Indicate whether the last method call succeeded or failed. A value of true indicates success, a value of false indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = true and failure = false.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to true. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

public int NumChannels {get; }

The number of channels in the RSS document.

public int NumItems {get; }

The number of items in the channel.

public bool VerboseLogging {get; set; }

If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

public string Version {get; }

Version of the component/library, such as "9.4.1.42"

Methods

public Rss AddNewChannel();

Adds a new channel to the RSS document. Returns the Rss object representing the Channel which can then be edited.

public Rss AddNewImage();

Adds a new image to the RSS document. Returns the Rss object representing the image, which can then be edited.

public Rss AddNewItem();

Adds a new Item to an Rss channel. Returns the Rss object representing the item which can then be edited.

(awaitable) public IAsyncOperation<bool> DownloadRssAsync(string url);

Downloads an RSS document from the Internet and populates the Rss object with the contents.

Returns true for success, false for failure.

Example: Read RSS Feed

public string GetAttr(string tag, string attrName);

Returns the value of a sub-element attribute. For example, to get the value of the "isPermaLink" attribute of the "guid" sub-element, call item.GetAttr("guid","isPermaLink").

Returns null on failure

public Rss GetChannel(int index);

Returns the Nth channel of an RSS document. Usually there is only 1 channel per document, so the index argument should be set to 0.

public int GetCount(string tag);

Return the number of sub-elements with a specific tag.

public string GetDateStr(string tag);

The same as GetDate, except the date/time is returned in RFC822 string format.

Returns null on failure

public Rss GetImage();

Return the image associated with the channel.

public int GetInt(string tag);

Return the value of a numeric sub-element as an integer.

public Rss GetItem(int index);

Return the Nth item of a channel as an RSS object.

public string GetString(string tag);

Return the value of an sub-element as a string.

Returns null on failure

public bool LoadRssFile(string filePath);

Load an RSS document from a file.

Returns true for success, false for failure.

public bool LoadRssString(string rssString);

Loads an RSS feed document from an in-memory string.

Returns true for success, false for failure.

public string MGetAttr(string tag, int index, string attrName);

Get an attribute value for the Nth sub-element having a specific tag. As an example, an RSS item may have several "category" sub-elements. To get the value of the "domain" attribute for the 3rd category, call MGetAttr("category",2,"domain").

Returns null on failure

public string MGetString(string tag, int index);

Get the value of the Nth occurance of a sub-element. Indexing begins at 0.

Returns null on failure

public bool MSetAttr(string tag, int idx, string attrName, string value);

Set an attribute on the Nth occurance of a sub-element.

Returns true for success, false for failure.

public bool MSetString(string tag, int idx, string value);

Set the value of the Nth occurance of a sub-element. Indexing begins at 0.

Returns true for success, false for failure.

public void NewRss();

Clears the RSS document.

public void Remove(string tag);

Removes a sub-element from the RSS document.

public bool SaveLastError(string path);

Saves the last-error information (the contents of LastErrorXml) to an XML formatted file.

Returns true for success, false for failure.

public void SetAttr(string tag, string attrName, string value);

Sets the value of a sub-element attribute.

public void SetDateNow(string tag);

Sets the value of a date/time sub-element to the current system date/time.

public void SetDateStr(string tag, string dateTimeStr);

The same as SetDate, except the date/time is passed as an RFC822 string.

public void SetInt(string tag, int value);

Sets the value of an integer sub-element.

public void SetString(string tag, string value);

Sets the value of a sub-element.

public string ToXmlString();

Returns the RSS document as an XML string.

Returns null on failure

Events

Callbacks from asynchronous methods occur in a background thread. However, controls on the UI thread may only be accessed from the UI thread.Therefore, UI updates must be dispatched to the UI thread. One way to do this is as follows:

    public sealed partial class MainPage : Page
    {
        private Windows.UI.Core.CoreDispatcher m_dispatcher = null;

        public MainPage()
        {
            this.InitializeComponent();
            m_dispatcher = Windows.UI.Core.CoreWindow.GetForCurrentThread().Dispatcher;
        }


        async private void Http_ProgressInfo(object sender, Chilkat.ProgressInfoEventArgs eventArgs)
        {
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
                // Application code to update the UI goes here...
            });
        }

    }

public event AbortCheckEventHandler AbortCheck;

Provides the opportunity for a method call to be aborted. The AbortCheck event is fired periodically based on the value of the HeartbeatMs property. If HeartbeatMs is 0, then no AbortCheck events will fire. As an example, to fire 5 AbortCheck events per second, set the HeartbeatMs property equal to 200.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.AbortCheckEventArgs

Event callback implementation:

private void rss_AbortCheck(object sender, Chilkat.AbortCheckEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Rss rss = new Chilkat.Rss();
rss.AbortCheck += rss_AbortCheck;

public event BinaryDataEventHandler BinaryData;

Binary data provided by certain methods.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.BinaryDataEventArgs

Event callback implementation:

private void rss_BinaryData(object sender, Chilkat.BinaryDataEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Rss rss = new Chilkat.Rss();
rss.BinaryData += rss_BinaryData;

public event PercentDoneEventHandler PercentDone;

Provides the percentage completed for any method that involves network communications or time-consuming processing (assuming it is a method where a percentage completion can be measured). This event is only fired when it is possible to know a percentage completion, and when it makes sense to express the operation as a percentage completed. The pctDone argument will have a value from 1 to 100. For operations (Chilkat method calls) that complete very quickly, the number of PercentDone callbacks will vary, but the final callback should have a value of 100. For long running operations, no more than one callback per percentage point will occur (for example: 1, 2, 3, ... 98, 99, 100).

The PercentDone callback counts as an AbortCheck event. For method calls that complete quickly such that PercentDone events fire, it may be that AbortCheck events don't fire because the opportunity to abort is already provided in the PercentDone callback. For time consuming operations, where the amount of time between PercentDone callbacks are long, AbortCheck callbacks may be used to allow for the operation to be aborted in a more responsive manner.

The abort output argument provides a means for aborting the operation. Setting it to true will cause the method to abort and return a failed status (or whatever return value indicates failure).

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.PercentDoneEventArgs

Event callback implementation:

private void rss_PercentDone(object sender, Chilkat.PercentDoneEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Rss rss = new Chilkat.Rss();
rss.PercentDone += rss_PercentDone;

public event ProgressInfoEventHandler ProgressInfo;

A general name/value event that provides information about what is happening during a method call. To find out what information is available, write code to handle this event and log the name/value pairs. Most are self-explanatory.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.ProgressInfoEventArgs

Event callback implementation:

private void rss_ProgressInfo(object sender, Chilkat.ProgressInfoEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Rss rss = new Chilkat.Rss();
rss.ProgressInfo += rss_ProgressInfo;

public event TaskCompletedEventHandler TaskCompleted;

Called in the background thread when an asynchronous task completes.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.TaskCompletedEventArgs

Event callback implementation:

private void rss_TaskCompleted(object sender, Chilkat.TaskCompletedEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Rss rss = new Chilkat.Rss();
rss.TaskCompleted += rss_TaskCompleted;

public event TextDataEventHandler TextData;

Text data provided by certain methods.

Chilkat WinRT C# Event Implementation

Args are passed using Chilkat.TextDataEventArgs

Event callback implementation:

private void rss_TextData(object sender, Chilkat.TextDataEventArgs args)
	{
            await m_dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
            {
	        // The event callback is not in the main UI thread.  To safely update UI elements, encapsulate
                // application code in this way.
            });
	}

To add an event handler:

Chilkat.Rss rss = new Chilkat.Rss();
rss.TextData += rss_TextData;